refactor(expr): JsonTree — un-pickable trees still expand + drop dead clickable var

frontend/src/expr/JsonTree.test.tsx

@@ -54,6 +54,13 @@ describe("JsonTree", () => {
     expect(onPick).not.toHaveBeenCalled();
   });
 
+  it("branches still expand when pickable is false (an un-pickable tree stays browsable)", async () => {
+    render(<JsonTree value={{ a: { b: 2 } }} pickable={false} />);
+    expect(screen.queryByText("b")).not.toBeInTheDocument();
+    await userEvent.click(screen.getByText("a"));
+    expect(screen.getByText("b")).toBeInTheDocument();
+  });
+
   it("renders empty state for empty object", () => {
     render(<JsonTree value={{}} />);
     expect(screen.getByText(/no data/i)).toBeInTheDocument();

frontend/src/expr/JsonTree.tsx

@@ -54,11 +54,12 @@ function Node({ label, value, path, depth, pickable, onPick }: NodeProps) {
 function BranchOrLeaf({ label, value, path, depth, pickable, onPick }: NodeProps) {
   const branch = isBranch(value);
   const [open, setOpen] = useState(false);
-  const clickable = pickable;
+  // Branches always expand/collapse (so an un-pickable tree can still be
+  // browsed — e.g. the Output column in the node editor dialog). Only leaf
+  // clicks are gated by `pickable`.
   const pickHandler = () => {
-    if (!pickable) return;
-    if (branch) setOpen((o) => !o);
-    else onPick?.(path);
+    if (branch) { setOpen((o) => !o); return; }
+    if (pickable) onPick?.(path);
   };
   return (
     <li>
@@ -67,8 +68,8 @@ function BranchOrLeaf({ label, value, path, depth, pickable, onPick }: NodeProps
         onClick={pickHandler}
         className={
           "flex items-center gap-1 w-full text-left py-0.5 px-1 rounded " +
-          (pickable ? "hover:bg-slate-800/80 " : "opacity-50 cursor-default ") +
-          (clickable ? "" : "cursor-default")
+          "hover:bg-slate-800/80 " +
+          (!pickable && !branch ? "opacity-50 cursor-default" : "")
         }
       >
         {branch ? (open ? <ChevronDown size={12} /> : <ChevronRight size={12} />) : <span className="w-3" />}